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Acta Geologica Sinica(English Edition) 2020年第5期94卷 1440-1450页

作者： Asghar ALI Khaista rehman Owais TAYYAB Tahir ZAmAN mahad JAmEEL Azeem KHAN Rafique AHmAD muhammad IRFAN Department of Geology University of PeshawarKhyber Pakhtunkhwa 25120Pakistan National Centre of Excellence in Geology University of PeshawarKhyber Pakhtunkhwa 25120Pakistan Department of Geology The Bacha Khan UniversityCharsadda24420Pakistan

Analysis of the anomalous magnetic mineral intensities and geochemistry for placer gold deposits are presented for those of the Attock area at the confluence of the Indus and Kabul rivers in northwestern *** grids covering an area of 10 x18 m2 and 8 x10 m2 were analyzed using a G-858 Cesium Vapor *** anomalous zones obtained were plotted on contour maps,2 D and 3 D magnetic intensity *** on the magnetic anomalies,grid-1 of the study area was sampled at three different anomalous zones for geochemical *** zones contain gold concentrations,ranging from 2.11 ppm to 6.109 ppm with an average of 4.01 *** in gold concentration in the subsurface within the anomalous zones indicates that magnetometer survey followed by a geochemical analysis can potentially narrow down the gold-bearing anomalous zones.

关键词： geochemistry geophysics placer gold deposits magnetometer survey anomalous zones Pakistan

Comparative cyclic oxidation behaviour and effect of oxides on hardness of wear resistance coating alloys T-401 and T-900

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Journal of Iron and Steel Research International 2019年第10期26卷 1069-1079页

作者： Abdul rehman Yang Liang mohammad Hassan Shirani Bidabadi Zheng Yu Chi Zhang Hao Chen Zhi-gang Yang Key Laboratory of Advanced materials Ministry of EducationSchool of Materials Science and EngineeringCollaborative Innovation Center of Advanced Nuclear Energy TechnologyTsinghua UniversityBeijing 100084China

The investigated alloys are newly developed Tribaloy alloys with enhanced crack and oxidation resistance over the traditional Tribaloy *** cyclic oxidation performance and effects of complex oxides on the hardness of cobaltbased Tribaloy alloys T-401(hypoeutectic)and T-900(hypereutectic)were *** results showed that T-900 alloy has a lower oxidation rate as compared to T-401 alloy at 800 and 1000℃,which attributed to the formation of dense continuous Cr2O3 layer with an upper thinner continuous layer of CoCr2O4 and NiCr2O4 *** 1000℃,T-401 alloy exhibited poor oxidation resistance due to severe spallation after 3 cycles(45 h).After oxidation,T-900 alloy exhibits 98%and 18%lower mass gain than T-401 alloy at 1000 and 800℃,*** T-900 alloy,relationship between mass gain and thickness of oxide layer revealed that mass will increase 0.162 mg/cm2 for every 1-μm increase in the oxides *** SiO2 oxide was observed at 800 and 1000℃for both ***,the extent of internal Si oxides increased with increasing oxidation temperature from 800 to 1000℃.Consequently,internal oxidation of Si led to the formation of Laves phase-depleted region near oxide/alloy interface in T-900 alloy at 1000℃.Thus,hardness of T-900 alloy decreased from 618 to 392 HV beneath the oxide/alloy interface at 1000℃,whereas hardness of T-900 and T-401 alloys after cyclic oxidation test at 800℃increased from 618 to 855 and 519 to 685 HV,respectively.

关键词： Tribaloy Hypoeutectic alloy Hypereutectic alloy Cyclic oxidation Depletion Nitride Hardness

Extreme Temperature Trends on the West Coast of Saudi Arabia

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Atmospheric and Climate Sciences 2012年第3期2卷 351-361页

作者： Shafiqur rehman Luai m. Al-Hadhrami Center for Engineering Research Research Institute King Fahd University of Petroleum and Minerals Dhahran Saudi Arabia

The extreme temperature trends are analyzed for a meteorological data collection station in Jeddah, Saudi Arabia over approximately last four decades stretching between years 1970 and 2006. The long-term change in temperature has been assessed by mann-Kendell rank statistics and linear trend analysis. The study also includes the estimation of hot and cold days and nights frequencies and finally the temperature anomalies on yearly basis. The ratio between the seasonal mean temperatures (Tmmean) of the daily mean of hottest (July) and coldest (January) months was 1.032. Similarly the ratios between the seasonal mean temperature of daily maximum (Tmmax) of hottest and coldest months was 1.033 while for seasonal mean temperature of daily minimum (Tmmin) was 1.030. Significant increase was observed in hot days per year and relatively smaller decrease in hot nights. Significant increase in summer time temperatures was confirmed by both linear regression analysis and m-K rank statistics. The monthly and annual mean maximum temperatures have increased more than the mean and mean minimum temperatures.

关键词： Global Warming Extreme Temperatures Temperature Trends

An Efficient Impersonation Attack Detection method in Fog Computing

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Computers, materials & Continua 2021年第7期68卷 267-281页

作者： Jialin Wan muhammad Waqas Shanshan Tu Syed mudassir Hussain Ahsan Shah Sadaqat Ur rehman muhammad Hanif Engineering Research Center of Intelligent Perception and Autonomous Control Faculty of Information TechnologyBeijing University of TechnologyBeijing100124China Faculty of Computer Science and Engineering Ghulam Ishaq Khan Institute of Engineering Sciences and TechnologyTopi23460Pakistan Department of Electronics Engineering FICTBalochistan University of Information TechnologyEngineering and Management SciencesQuetta87300Pakistan Department of Computer Science Namal InstituteMianwali42200Pakistan

Fog computing paradigm extends computing,communication,storage,and network resources to the network’s *** the fog layer is located between cloud and end-users,it can provide more convenience and timely services to ***,in fog computing(FC),attackers can behave as real fog nodes or end-users to provide malicious services in the *** attacker acts as an impersonator to impersonate other legitimate ***,in this work,we present a detection technique to secure the FC ***,we model a physical layer key generation based on wireless channel *** generate the secret keys between the legitimate users and avoid impersonators,we then consider a Double Sarsa technique to identify the impersonators at the receiver *** compare our proposed Double Sarsa technique with the other two methods to validate our work,i.e.,Sarsa and *** simulation results demonstrate that the method based on Double Sarsa outperforms Sarsa and Q-learning approaches in terms of false alarm rate(FAR),miss detection rate(mDR),and average error rate(AER).

关键词： Fog computing double Sarsa attack detection physical layer key security

Exogenous Selenium mitigates Salt Stress in Soybean by Improving Growth,Physiology,Glutathione Homeostasis and Antioxidant Defense

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Phyton-International Journal of Experimental Botany 2021年第2期90卷 373-388页

作者： Hesham F.Alharby mirza Hasanuzzaman Hassan S.Al-Zahrani Khalid rehman Hakeem Department of Biological Sciences Faculty of ScienceKing Abdulaziz UniversityJeddah21589Saudi Arabia Department of Agronomy Sher-e-Bangla Agricultural UniversityDhaka1207Bangladesh

The mechanism of selenium(Se)-induced salt tolerance was studied in moderately sensitive soybean(Glycine max L.)*** execute this view,soybean plants were imposed with salt stress(EC 6 dS m^(−1))applying *** other treatments,Se(0,25,50 and 75μm Na_(2)SeO_(4))was sprayed as co-application with that level of salt *** height,stem diameter,leaf area,SPAD value decreased noticeably under salt *** proline(Pro)level,together with decreased leaf relative water content(RWC)was observed in salt-affected *** stress resulted in brutal oxidative damage and increased the content of H_(2)O_(2),mDA level and electrolyte *** Se spray alleviated oxidative damage through boosting up the antioxidant defense system by increasing the activity of antioxidant enzymes such as catalase(CAT),peroxidase(POD)and glutathione reductase(GR),as well as by improving non-enzymatic antioxidants like glutathione(GSH)and GSH/glutathione disulfide(GSSG).The upregulated antioxidant defense system,restored Pro and leaf RWC,higher SPAD value conferred better growth and development in Se-sprayed salt-affected soybean plants which altogether put forth for the progressive yield contributing parameters and finally,seed *** different doses of Se,soybean plants sprayed with 50μm Na_(2)SeO_(4)showed better salt tolerance.

关键词： Trace elements selenium antioxidant system oxidative stress salinity oilseed crop

Electron doping induced semiconductor to metal transitions in ZrSe2 layers via copper atomic intercalation

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Nano Research 2018年第9期11卷 4914-4922页

作者： Zahir muhammad Kejun mu Haifeng Lv Chuanqiang Wu Zia ur rehman muhammad Habib Zhe Sun Xiaojun Wu Li Song National Synchrotron Radiation Laboratory CAS Center for Excellence in Nanoscience CAS Key Laboratory of Strongly-coupled Quantum Matter Physics University of Science and Technology of China Hefei 230029 China CAS Key Laboratory of materials for Energy Conservation Synergetic Innovation Centre of Quantum Information & Quantum Physics CAS Center for Excellence in Nanoscience and Department of Material Science and Engineering University of Science and Technology of China Hefei 230026 China

Atomic intercalation in two-dimensional （2D） layered materials can be used to engineer the electronic structure at the atomic scale and generate tuneable physical and chemical properties which are quite distinct in comparison with the pristine material. Among them, electron-doped engineering induced by intercalation is an efficient route to modulate electronic states in 2D layers. Herein, we demonstrate a semiconducting to metallic phase transition in zirconium diselenide （ZrSe2） single crystals via controllable incorporation of copper （Cu） atoms. Our angle resolved photoemission spectroscopy （ARPES） measurements and first-principles density functional theory （DFT） calculations dearly revealed the emergence of conduction band dispersion at the m/L point of the Brillouin zone due to Cu-induced electron doping in ZrSe2 interlayers. moreover, electrical measurements in ZrSe2 revealed semiconducting behavior, while the Cu-intercalated ZrSe2 exhibited a linear current-voltage curve with metallic character. The atomic intercalation approach may have high potential for realizing transparent electron-doping systems for many specific 2D-based nanoelectronic applications.

关键词： layered materials phase transition angle resolved photoemission spectroscopy electron doping

Concentration and Temperature Dependence of Electrical Conductivity in Thermally Stable Chromium Polyacrylate

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Journal of materials Science & Technology 1995年第6期11卷 443-446页

作者： S. U.rehman m.Siddique and Farid A.Khwaja(materials Research Laboratory, Dept. of Physics, Quaid-i-Azam University, Islamabad, Pakistan)m.S.Zafar(Dept. of Physics, University of the Punjab, Lahore, Pakistan) Quaid-i-Azam Univ Islamabad Pakistan

Electrical conductivity of chromium polyacrylate with dopant concentration 30, 40 and 50 wt-% of chromium has been measured over a broad range of temperatures (303 K to 383 K).The electrical conductivity shows dependence on temperature, as well as, level of doping. The conductivity is considered to be due to thermal hopping motion of localized charge carriers,which are believed to be polarons, in the temperature range 303 K to 323 K and for T>343 K,whereas. it is metal-like in the temperature range 323 K to 343 K

关键词： Concentration and Temperature Dependence of Electrical Conductivity in Thermally Stable Chromium Polyacrylate

magnetic-field-driven reverse martensitic transformation with multiple magneto-responsive effects by manipulating magnetic ordering in Fe-doped Co-V-Ga Heusler alloys

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Journal of materials Science & Technology 2020年第23期58卷 145-154页

作者： Kai Liu Shengcan ma Yuxi Zhang Hai Zeng Guang Yu Xiaohua Luo Changcai Chen Sajjad Ur rehman Yongfeng Hu Zhenchen Zhong Jiangxi Key Laboratory for Rare Earth magnetic materials and Devices/Institute for Rare Earth magnetic materials and Devices(IREmmD) Jiangxi University of Science and TechnologyGanzhou 341000China School of materials Science and Engineering Jiangxi University of Science and TechnologyGanzhou 341000China Canadian Light Source University of SaskatchewanSaskatoonSaskatchewan S7N 2V3Canada

Nowadays,searching for the materials with multiple magneto-functional properties and good mechanical properties is vital in various fields,such as solid-state refrigeration,magnetic actuators,magnetic sensors and intelligent/smart *** this work,the magnetic-field-induced metamagnetic reverse martensitic transformation(mFIRmT)from paramagnetic martensite to ferromagnetic austenite with multiple magneto-responsive effects is realized in Fe-doped Co-V-Ga Heusler alloys by manipulating the magnetic *** martensitic transformation temperature Tmreduces quasi-linearly with increasing *** strikingly contrast with the Fe-free alloys,the magnetization difference(m')across martensitic transformation increases by three orders of magnitude for Fe-doped *** increased m'should be ascribed to the reduction of Tm,almost unchanged Curie temperature of austenite and the increased magnetic moment in the samples with higher *** large m'provides strong driving force to realize the mFIRmT and accordingly multiple magneto-responsive effects,such as magnetocaloric,magnetoresistance and magnetostriction ***,giant Vickers hardness of 518 HV and compressive strength of 1423 mPa are *** magneto-responsive effects with exceptional mechanical properties make these alloys great potential candidates for applications in many fields.

关键词： magneto-functional properties mechanical properties Ferromagnetic ordering Reverse martensitic transformation multiple magneto-responsive effects Co-based Heusler alloys

Enhancement of terbium efficiency by gallium and copper co-doping in(Pr,Nd)-Fe-B sintered magnets

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Journal of Rare Earths 2023年第4期41卷 572-577页

作者： Qingfang Huang Qingzheng Jiang Yao Shi Sajjad Ur rehman Xing Wei Ruoshu Wang Yongjian Zhang Deqin Xu Dakun Chen Zhenchen Zhong Jiangxi Key Laboratory for Rare Earth magnetic materials and Devices&College of Rare Earth Jiangxi University of Science and TechnologyGanzhou 341000China Institute of Rare Earth magnetic material Xiamen Tungsten Co.Ltd.Xiamen 361010China Fujian Key Laboratory for Rare Earth Functional materials Longyan 366300China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou 341000China

It is well known that Tb substitution for(Pr,Nd)in(Pr,Nd)-Fe-B based sintered magnetic materials is an effective way to increase intrinsic coercivity,but it is not quite clear whether the increment depends on the different matrix phases with various doping ingredient or not,which is essential to develop high quality magnets with high coercivity more efficiently and effectively with economic consumption of expensive Tb and other costly heavy rare *** this paper,we investigated the efficiency of Tb substitution for magnetic property in(Pr,Nd)-Fe-B sintered permanent magnets by co-doping Ga and Cu *** is shown that Ga and Cu co-doping can effectively improve the efficiency of Tb substitution to increase the thermal stability and the *** intrinsic coercivity increases up to 549 and 987 kA/m respectively by 1.5 wt%and 3.0 wt%Tb substitution in Ga and Cu co-doped magnets while the intrinsic coercivity increases up to only 334 and 613 kA/m respectively by the same amounts of Tb substitution in non-Ga and low-Cu *** other words,it demonstrates that there is about 329-366 kA/m linear equivalent enhancement of intrinsic coercivity by 1.0 wt%Tb substitution for(Pr,Nd)in Ga and Cu co-doped *** temperature coefficients of both intrinsic coercivityβand remanenceαat 20-150℃by 3.0 wt%Tb substitution for the magnets with Ga and Cu co-doping are-0.47%/K and-0.109%/K respectively,and in contrast those values are-0.52%/K and 0.116%/K respectively for the non-Ga and low-Cu *** is the principal reason for more efficient enhancement of magnetic property by Tb substitution in the Ga and Cu co-doped magnets in which Tb atoms are expelled from triple junction phases(TJPs)to penetrate into the grain boundary phases(GB phases)and thus modify the grain *** is prospected that the efficiency of Tb substitution would rely on different matrix phases with various doping constituents.

关键词： (Pr Nd)-Fe-B magnet magnetic properties microstructure Efficiency of Tb substitution Ga and Cu co-doping Rare earths

Extraordinary simultaneous enhancement of the coercivity and remanence of dual alloy HRE-free Nd-Fe-B sintered magnets by post-sinter annealing

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Journal of materials Science & Technology 2022年第11期106卷 236-242页

作者： Qingfang Huang Qingzheng Jiang Jifan Hu Sajjad Ur rehman Gang Fu Qichen Quan Jixiang Huang Deqin Xu Dakun Chen Zhenchen Zhong Jiangxi Key Laboratory for Rare Earth magnetic materials and Devices&College of Rare Earths Jiangxi University of Science and TechnologyGanzhou 341000China Fujian Key Laboratory for Rare Earth Functional materials Longyan 366300China School of materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan 030024China

Post-sinter annealing process plays an important role in the microstructures and magnetic properties of the Nd-Fe-B sintered *** this paper,systematically investigated are the magnetic properties and microstructures of the as-sintered and post-sinter annealed Nd-Fe-B magnets with Pr-Fe-Ga boundary *** choice consecutive annealing methods are adopted at high and low temperatures,namely the 1 st annealing at 880℃ for 2 h and then the 2^(nd) annealing at 440℃ for 3 *** is exceptional to find out that both the remanence and coercivity are improved after 2^(nd) annealing process for this type of *** coercivity is hugely increased from 10.09 kOe for the as-sintered sample to 17.19 kOe for the 2^(nd) annealed magnet,with a significant increment of 70.37%in *** extraordinary magnetic properties of B_(r)=14.44 kGs,H_(cj)=17.19 kOe and(BH)_(max)=51.08 mGOe are obtained for the designated Nd-Fe-B sintered magnets without heavy rare earth(HRE)elements manufactured by dual alloy *** Curie temperature is monotonically decreased from 634 K to 602 K while the c-axis alignment degree is optimized after *** observation and analysis indicate that the elemental distribution patterns are altered after the 2^(nd) *** diffusion of the aggregate(Pr,Nd,Cu,Ga)-rich phase from triple junctions into the grain boundary regions is ascribed to the formation of thin and continuous grain boundary layer,which is critical to improve the microstructures and magnetic properties.

关键词： Nd-Fe-B sintered magnets HRE-free Dual alloy method Post-sinter annealing magnetic properties